Conventionally, this kind of lawn mower has been structured such as to continuously mow lawn grass standing on a ground surface by the lawn mowing mechanism and collect the grass in the grass collection box via a discharge duct extending rearward from the lawn mowing mechanism. One example of the lawn mower is disclosed in Patent Documents 1 and 2.
The lawn mowers in the patent documents 1 and 2 are of a so-called high dump specification, and are provided with a lift mechanism for lifting up a grass collection box to a predetermined height position. A rear surface opening portion of the grass collection box is closed by a rear lid plate which can be opened and closed. In this case, since the grass collection box is rotated so as to change its attitude in such a manner that the rear surface opening portion is directed downward (faces to the ground surface) while opening the rear lid plate after lifting up the grass collection box filled with the mowed grass to the predetermined height position by driving the lift mechanism, the mowed grass in the grass collection box is discharged to a container, a loading platform of a truck or the like from the high position.    Patent Document 1: Japanese Unexamined Patent Publication No. 2001-275438    Patent Document 2: Japanese Unexamined Patent Publication No. 2002-84950